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Scan all buffered data looking for JPEG end

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This is much more efficient than looking at two bytes at a time.
This commit is contained in:
Pierre Ossman
2025-09-03 11:24:34 +02:00
parent d5b18a84ab
commit 356eab4f4d
1 changed files with 23 additions and 8 deletions
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33
core/decoders/jpeg.js
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@@ -119,18 +119,33 @@ export default class JPEGDecoder {
let extra = 0;
if (type === 0xDA) {
// start of scan
extra += 2;
while (true) {
if (sock.rQwait("JPEG", length-2+extra, 4)) {
if (sock.rQwait("JPEG", length-2 + 2, 4)) {
return null;
}
let data = sock.rQpeekBytes(length-2+extra, false);
if (data.at(-2) === 0xFF && data.at(-1) !== 0x00 &&
!(data.at(-1) >= 0xD0 && data.at(-1) <= 0xD7)) {
extra -= 2;
break;
let len = sock.rQlen();
let data = sock.rQpeekBytes(len, false);
while (true) {
let idx = data.indexOf(0xFF, length-2+extra);
if (idx === -1) {
sock.rQwait("JPEG", Infinity, 4);
return null;
}
extra++;
if (idx === len-1) {
sock.rQwait("JPEG", Infinity, 4);
return null;
}
if (data.at(idx+1) === 0x00 ||
(data.at(idx+1) >= 0xD0 && data.at(idx+1) <= 0xD7)) {
extra = idx+2 - (length-2);
continue;
}
extra = idx - (length-2);
break;
}
}